{"id":8453,"date":"2024-02-01T13:30:30","date_gmt":"2024-02-01T18:30:30","guid":{"rendered":"https:\/\/latinamericasecurityreport.com\/?p=8453"},"modified":"2024-02-01T13:30:30","modified_gmt":"2024-02-01T18:30:30","slug":"study-shows-that-rio-grande-rise-was-once-a-giant-mineral-rich-tropical-island-near-brazil","status":"publish","type":"post","link":"https:\/\/latinamericasecurityreport.com\/?p=8453","title":{"rendered":"Study Shows That Rio Grande Rise Was Once a Giant Mineral-Rich Tropical Island near Brazil"},"content":{"rendered":"
Samples were collected during expeditions conducted in 2018 by researchers affiliated with the University of S\u00e3o Paulo (Brazil) and the University of Southampton (UK). This dark-gray rock is a volcanic basalt deposit<\/figcaption><\/figure>\n

A study led by scientists at the University of S\u00e3o Paulo (USP) in Brazil has shown that the Rio Grande Rise (RGR), a possibly continental basaltic plateau and chain of seamounts now submerged in the South Atlantic Ocean some 1,200 km from the coast of Brazil, was once a giant tropical island, rich in minerals and covered with vegetation. Geologists have dated sediments from the formation to between 45 million and 40 million years ago.<\/p>\n

An article describing the results of the study, which involved almost ten years of research, is published<\/a> in the journal Scientific Reports<\/em> with new information on the geology of the RGR, which has about the same area as Spain.<\/p>\n

The researchers analyzed samples of seafloor sediment dredged at a depth of about 650 m in the western RGR and characterized its mineralogical, geochemical and magnetic properties. The samples contained mainly red clay with several minerals typical of tropical volcanic rock alterations, such as kaolinite, magnetite, oxidized magnetite, hematite and goethite.<\/p>\n

In 2018, the group posited that the RGR was once an island, based on discoveries made by scientific expeditions to the region, where they collected the sample described in the article (read more at: agencia.fapesp.br\/29617<\/a><\/em>). They traveled on the Royal Research Ship (RRS) Discovery<\/em>, operated by the United Kingdom\u2019s National Oceanography Center (NOC), and the Alpha Crucis<\/em>, USP\u2019s oceanographic research vessel. The expeditions were part of a Thematic Project supported by FAPESP<\/a>. The researchers were from USP\u2019s Oceanographic Institute (IO) and the University of Southampton in the UK.<\/p>\n

\u201cOur research and analysis enabled us to determine that it was indeed an island, and what\u2019s now under discussion is whether the area can be included in Brazil\u2019s legally recognized continental shelf. Geologically speaking, we discovered that the clay was formed after the last volcanic activity occurred 45 million years ago. The formation therefore dates from between 30 million and 40 million years ago. And it must have been formed as a result of these tropical conditions,\u201d Luigi Jovane<\/a>, last author of the article and a professor at IO-USP, told Ag\u00eancia FAPESP.<\/p>\n

For Jovane, who is the principal investigator for a project funded by FAPESP<\/a>, the fact that a multidisciplinary team participated in the research contributed to the results. \u201cWe have a group of the highest quality including specialists in geology, geochemistry, biology, hydrodynamics, environmental impact assessment, new energies, psychology, and law. All this accumulated science can be used to deepen our understanding of the RGR and prospect the region without affecting the local system\u2019s synergies. To know whether resources can be viably extracted from the seafloor, we need to analyze the sustainability and impacts of this extraction. The ecosystem services provided by the ocean there haven\u2019t been studied in detail, for example. When you interfere with an area, you have to know how this will affect animals, fungi and corals, and understand the impact you\u2019ll have on the cumulative processes involved,\u201d Jovane said.<\/p>\n

Priyeshu Srivastava<\/strong><\/a>, first author of the article and currently a professor at the University of Mumbai in India, was also supported by FAPESP via two projects (19\/11364-0<\/strong><\/a> and 22\/02479-0<\/strong><\/a>).<\/p>\n

In 2023 alone, Jovane led the production of four other articles with results of studies involving volcanic rock and ferromanganese crust samples from the RGR. The articles are published in Frontiers in Marine Science<\/strong><\/a><\/em>, Journal of Materials Research and Technology<\/strong><\/em><\/a>, Geochemistry<\/strong><\/em><\/a> and Marine Geology<\/strong><\/em><\/a>).<\/p>\n

Seafloor discoveries<\/strong><\/p>\n

The scientists focused on the western portion of the RGR, which they reconstructed by high-resolution bathymetric mapping that showed plateaus covered with sediment and separated by a rift with a depth of more than 600 m. They used an autonomous underwater vehicle (AUV) and a remotely operated vehicle (ROV) from the Discovery<\/em> to produce maps, videos and sonar surveys.<\/p>\n

The AUV is capable of diving down to the seafloor and covering a pre-established area for a maximum of 12 hours. The ROV is connected to the ship by a cable as it moves while producing high-resolution images, and collecting samples of rocks and organisms with a robotic arm. \u201cNo one in Brazil has AUVs or ROVs, so partnering with our British colleagues at the NOC was fundamental, but the research is 100% Brazilian,\u201d Jovane said.<\/p>\n

The existence of tropical soil between the volcanic lava flows detected by the researchers shows that the rocks must have been exposed to open-air weathering in a warm-wet climate in a region with active volcanoes less than 40 million years ago. The soil is similar to the \u201cred earth\u201d (terra roxa<\/em>) found in many parts of S\u00e3o Paulo state, according to Jovane.<\/p>\n

The most widely used measure of rock weathering, known as the chemical index of alteration (CIA), was 93 for the red clay. Most alkaline rocks have a CIA of less than 50. This high value points to its origin in extreme weathering of lava flows and volcanic rocks during the Eocene (the second epoch of the Paleogene Period) between 56 million and 34 million years ago, when high temperatures favored the development of tropical forests, before the sudden climate changes that occurred when Australia split off rapidly from Antarctica. The open-air erosion was followed by thermal subsidence and submergence during the late Eocene and early Oligocene between 35 million and 25 million years ago.<\/p>\n

The RGR has been intensely studied in recent years because of its economic potential. It is in international waters and hence governed by the International Seabed Authority (ISA<\/strong><\/a>). In December 2018, the Brazilian government applied for an extension of its continental shelf to include the RGR, which is well beyond the limit of 200 nautical miles established for all nations by the UN Convention on the Law of the Sea (UNCLOS). <\/p>\n

Areas rich in cobalt, nickel and lithium, as well as tellurium and other rare earths critical to the transition from fossil fuels, one of the main drivers of global warming, to renewable energy, have been detected in the RGR. <\/p>\n

\u201cIt\u2019s important to understand the ecosystem services and other natural processes at work in the RGR,\u201d Jovane said. \u201cOnly this knowledge can enable us to carry out the environmental impact assessments and calculate the mitigation measures and offsets required to protect it if economic development is permitted.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

A study led by scientists at the University of S\u00e3o Paulo (USP) in Brazil has shown that the Rio Grande Rise (RGR), a possibly continental basaltic plateau and chain of seamounts now submerged in the South Atlantic Ocean some 1,200 km from the coast of Brazil, was once a giant tropical island, rich in minerals…<\/p>\n","protected":false},"author":124,"featured_media":8455,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ngg_post_thumbnail":0,"fifu_image_url":"https:\/\/earimediaprodweb.azurewebsites.net\/Api\/v1\/Multimedia\/67c01722-8ed5-41d8-abb6-c9ba76c900a4\/Rendition\/low-res\/Content\/Public","fifu_image_alt":"Study Shows That Rio Grande Rise Was Once a Giant Mineral-Rich Tropical Island near Brazil","footnotes":""},"categories":[195],"tags":[],"class_list":["post-8453","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-health-environment"],"_links":{"self":[{"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=\/wp\/v2\/posts\/8453","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=\/wp\/v2\/users\/124"}],"replies":[{"embeddable":true,"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=8453"}],"version-history":[{"count":1,"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=\/wp\/v2\/posts\/8453\/revisions"}],"predecessor-version":[{"id":8456,"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=\/wp\/v2\/posts\/8453\/revisions\/8456"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=\/wp\/v2\/media\/8455"}],"wp:attachment":[{"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=8453"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=8453"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/latinamericasecurityreport.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=8453"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}